Oil bath solenoid



March 14, 1961 Filed vay 7, 1956 H. W. JENCKS I'AL OIL BATH SOLENOID 5 Sheets-Sheet 1 BY ,5a/dgn f March 14, 1961 H. w. JENcKs HAL 2,975,340

OIL BATH SOLENOID 5 Sheets-Sheet 3 Filed vay 7, 1956 @Mn @pw March 14 1961 H. w. JENcKs HAL 2,975,340

OIL BATH SOLENOID Filed vay 7, 1956 5 Sheets-Sheet 4 Allflllonlllw u as 34 so@ IN VEN TORS Ho/s w. J-ewc-A/s Je BY fama/vo A. v4.15

Arfafwas March 14, 1961 H, w JENCKS ETAL 2,975,340

OIL BATH SOLENOID Filed vay 7, 1956 5 Sheets-Sheet 5 `sf/o eso United States Patent O 2,915,340 orL BATH SOLENOID Hollis W-Jencks, ,Ferndale and Edmnd A- Viale, Southfield Township, Oakland County, jMich., asdsignorrs to Detroit Coil Company, Ferndale', Mich., 'a corporation of Michigan Filed May 7, 1,9576, ser, isp., 583,323

1s anims. (ci. 317-185) This invention relates to solenoids and particularly to an oil bath solenoid.

This is a continuation-inpart application of our earlier tiled application, SerialNo. 479,-331,-ii led January 3, 1955, and `now abandoned.

Through the last vfew decades, an electrically operated device termed a solenoid has come into widespread use for actuating small mechanical devices. The Lsolenoid comprises generally a coil of wire adapted to be coupled with a source of electric power, with va plunger disposed adjacent the coil to be attracted theretoward or thereinto upon energization of the coil. The plunger is either coupled with or adapted to abut the device to be actuated by the solenoid. Countless varieties of uses have been made of solenoids, frequently in machines for applications wherein the solenoid is calledkuponto Vbe operated many thousands or millions of timesin the space of a t'ew months or a year. ln many of ythe, uses to which solenoids are put, they are located in `relatively inaccessible places requiring, for example, substantial disassembly of the associated machinery in order to repair or replace worn or inoperative parts of the solenoid. Frequent repair or replacement'of solenoids so located obviously is undesirable both from the standpoint of the cost of parts needing replacement and the `time and effort involved in making the replacement` necessitated by the disassembiy of machinery in which the solenoid is located, butalso through loss of the use of the machinery within whichl the solenoid is located.

There are a number of factors determinative of the lite of the solenoid. VOf these two Aare of prime importance, viz. the rapidity with which heat lis conveyed away from an operating solenoid and the amount of shock imposed onthe solenoid during its operation caused by the sudden arrests of the plungers movement at opposite ends of its stroke. Unless the heat generated by the solenoid during its operation is conveyed away as rapidly as it is formed, the temperature of the solenoid will rise, and if the temperature exceeds the melting point of insulation on the wire comprising the coil, the coilwill yshort out land proper operation of the solenoid vwill be impaired if not altogether prevented.

The shock encountered by the plunger at its sudden arrested movementsy at opposite ends of its stroke, tends to break up the plunger after extended operation. The meeting surfaces of the plunger and solenoid supporting frame which come together as the plunger is sucked into the solenoid, wear away, which, as more fully explained hereinafter, eventuallyhas a veryharmful effect on the solenoids operation. i

Any solution `to these problems, however, inworder to lgain commercialfavor, VVmust ,be intensely practical and must be embodied in a structurecapable'of manufacture at a. cost which, though exceeding' the cost'gofuconventional solenoids, isvt'ar .less .in proportion tothe increased light span of the solenoid. The improved solenoidfalso must ibet-capable-of jbeing ,mounted for V:operation in a ICC 2 simple manner and in the same positions and after the same fashion as a conventional solenoid. Y`-Therefore, an object of our invention is the provision of a solenoid unit having a life span far exceeding that of a conventional solenoid, and which may be manufactured at a cost substantially less rfor'its life span than a conven'- tional solenoid.` i An object of our invention is the provision of a solenoid unit which may be mounted, after the fashion of the conventional solenoid, directly upon a device to be actuated, such as a valve, switch, or the like, and which unit comprises an oil bath within which thefsolenoid operates, with the oil bath, thesolenoid, and a fluid sealing means, all compactly housed and novelly arranged with respect `to eachother. l v v Another object of the invention is the provisionof a solenoid unit adapted'to be mounted upon a device to be actuated, and which unit will convey away a substantial portion orf heat developed through the operation of Vvthe solenoid, and thereby permit a greater amount of electric current to be passed lthrough the solenoid thanis ordinarily possible without overheating the solenoid Another object of the invention is the provision of a solenoid unit of the above-mentioned,character which will function over a much greater length ottime and through a substantially greater number or" cycles than will the conventional solenoid, andkin which the movement of the plunger of the solenoid is dampened at the extreme opposite ends of its stroke.

Another object of the invention is the provision of an oil bath solenoid Whichis .mounted upon and removed from the device lto be actllated as a unit, and in which the operating mechanical connection between the unit and the device to be actuated as well Las the .electrical connection for energizing the unit are automatically effected when the unit is placed upon and secured to the device, and are automatically disconnected when the unit is unfastened and removed .from the device. With the attainment of this object, the installationand removal of an oil bathr solenoid unit requires the attention of only one workman, such as a hydraulics mechanic, where the device is ahydraulic valve. Heretofore, the installation or removal of a solenoid on any khydraulic equipment required the attendance, under union regulations, of an electrician to connect or disconnect the wires, and a hydraulics mechanic to connect or disconnect the securing means holding the solenoid on the equipment.

In one form of the invention the solenoid itself is resilientlyimounted withina housing and held in place within the housing against one end Wall thereof by spring means bearing against the solenoid and against an .opposite end wall of the housing, with the housing adapted to be secured to the device to be actuated.

Another object ofthe invention is the provision of a solenoid unit which is adapted to be mounted on a device to be actuated, and which unit includes an enclosure open at one end and within which a solenoid coil and plunger are disposed, with the enclosure filled with oil enveloping the solenoid, and with a ilexible diaphragm closing the open end of the enclosure and adapted to be flexed upon operation of the plunger of the Ysolenoid.` y `AAnother object of the invention is the provision of an oil bath solenoid unit having an actuating rod extending outwardly of the unit to actuate a device to vbe operated by the unit, with an improved oil sealing means encircling the rod to prevent the escape of oil outwardly of the unit, or the entrance of any Huid from the device being operated into the oil bath solenoid unit, and which means is vso constructed that any `movement of fluid along the rod Vthrough the sealing means is visually aident apen @spanien Of the enit.

Another object of the invention is the provision in a solenoid of a spacer pin disposed between the plunger of the solenoid and a part to be actuated by the plunger, which pin will cushion the shock of the plunger and materially prolong the life of the solenoid.

Still another object of the invention is the provision of an automatic lead wire connector for a solenoid wherein the connector will not only automatically couple the lead wires to a source of electric current when the solenoid is mounted on a device to be actuated, but will also serve to effectively uid-seal the entry of the lead wires to the solenoid.

Other objects, advantages, and meritorious features will more fully appear from the specification, claims, and accompanying drawing, wherein:

Fig. 1 is a top view of our oil bath solenoid unit taken on the line 1-1 of Fig. 2;

Fig. 2 is a cross sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary sectional view of the central portion of the diaphragm showing one form of the abutment member; l

Fig. 4 is a cross sectional view taken on the line 4 4 of Fig. 3;

Fig. 5 is a modification of the abutment member in the diaphragm;

Fig. 6 is another modied form of the abutment member in the diaphragm;

Fig. 7 is a fragmentary cross sectional view through a modiied form of our improved oil bath solenoid;

Fig. 8 is a detailed cross sectional View through one form of an improved lead wire sealing means;

Fig. 9 is a modified form of a resilient spacer pin;

Fig. l0 is a cross sectional view through an improved lead wire connector for a solenoid;

Fig. 11 is a cross sectional view throughanother form of the oil bath solenoid unit;

Fig. l2 is a cross sectional view taken on the line 12 12 of Fig. 11;

Fig. 13 is a cross sectional view taken on the line 13 13 of Fig. 11'; and

Fig. 14 is a cross sectional view taken on the line 14- 14 of Fig. 13. In the conventional solenoid there is provided a coil housed in a C-shaped or U-shaped frame. A plunger, generally T-shaped in configuration, is adapted to extend into the frame between the arms thereof and through the coll and lie in the plane of the frame with the underside of the head of the T-shaped plunger abutting the ends of the arms of the frame. Shading coils at the meeting faces of the underside of the head of the plunger and the ends of the arms conduct an out-of-phase current which tends to hold the plunger in a seated position against the ends of the arms of the frame. The shading coils function properly only so long as the underside of the head of the plunger and the ends of the arms of the frame abut each other throughout substantially their entire meeting surfaces. Once these meeting surfaces become peened or worn away, they permit the plunger to abut the bight portion of the frame and the contact between the head and the ends of the arms of the frame become uneven at the end of each arm. The shading coils then fail to function properly and the plunger chatters and eventually the coil burns. out.

A second cause of failure of solenoids is their tendency to overheat after long and continuous operation. This overheating is due to the inability of the heat generated during the operation of the solenoid to be conveyed away from the solenoid as rapidly as it is generated. The surface area of the solenoid exposed to the atmosphere is too small to permit adequate heat transfer from the solenoid to the atmosphere.

We have provided a solenoid unit which substantially prolongs the life of the solenoid which forms a cornponent of the unit because both of the above causes .0f

failure have been materially reduced if not eliminated. In carrying out the objects of our invention we provide an oil bath within which the'solenoid operates, with the oil both and the solenoid comprising a unit which may be mounted upon a device to be actuated. This unit, because it is capable of being mounted as such upon a device to be actuated, may be mounted in many different places, as, for example, in large machines, to actuate various parts of the machine. With the provision of our improved solenoid unit in which the solenoid will continue to function over a greater period of time than is presently possible with the conventional solenoids of today, the frequent repair of machinery embodying solenoids which are disposed in inaccessible places and whose failure causes breakdown of the machine, is materially reduced.

We have shown in Figs. 1 and 2 an illustrative embodiment of one form of our inmproved solenoid unit. The unit comprises a base 10 which is adapted to be mounted by means of the bolts 12 and 14 upon the device to be actuated by the solenoid. Such device is represented at 16 in the drawings and includes a stem 1S which leads to the operative mechanism in the device. The device is so constructed that upon urging of the stem 18 downwardly, the valve, switch, or whatever the mechanism of the device may be, will be actuated.

The base 10 is generally circular as shown in Fig. 1. The upper surface or face of the base is centrally recessed as at 20 to provide an upwardly opening well or the like. The sides of the well are defined by the annular wall 22 which extends upwardly from the oor 24 of the well. Centrally of the base 10 is an aperture 26 ex-I tending through the bottom wall 24 of the well and downwardly outwardly of the base. The bottom surface or face 27 of the base is adapted to rest against the device to be actuated and may be upwardly recessed as at 28 to accommodate the design of the device 16.

The base 10 is adapted to support the enclosure or housing 30 which houses the solenoid generally indicated at 32. The enclosure is supported upon the base by a plurality of screws or bolts 34, two of which are shown in Fig. 2. The enclosure 30 is generally cup-shaped and opens outwardly at that end connected to the base. An O-ring gasket or the like 36 is seated within a groove 3S formed in the side of the base, with the O-ring gasket adapted to bear against the enclosure and seal the connection between the enclosure` and the base.

In order to seal effectively the opening of the enclosure. the supporting means 10 includes a. flexible diaphragm 40 which cooperates with the supporting means to prevent the escape of oil within the enclosure outwardly of the solenoid unit. The diaphragm may be formed of sirvine, which is an artificial rubber somewhat like neoprene. embedded in and covering the opposite faces of a nylon web or the like. The neoprene-like rubber, as well as the nylon, is resistant to the destructive action of oil and therefore serves very well as a flexible seal for the unit. While a sirvine diaphragm has been mentioned specically, it is to be understood that diaphragms of other materials might serve as Well. The characteristics that the diaphragm must possess are that it must be formed of a material which will withstand the destructive effect of the fluid within the enclosure, it must be exible enough so that it will not materially impede the movement of the plunger of the solenoid as hereinafter described, it must be capable of withstanding millions of flexures without cracking, it must be substantially unstretchable so that through prolonged use it will not become larger and larger, and it must be capable of receiving, as hereinabove described, a centrally disposed abutment member which is connected to the diaphragm, without a tendency to rip or tear at the point of connection of the bearing and guiding member with the diaphragm.

The diaphragm is generally circular 1n shape and lhado formed during its fabrication to lexhibit Van annularpleat or the like as .at 42, which -pleat .is spaced from the perimeter of the diaphragm vand adapted -to be disposed within the well 20 of the base. The diaphragm, as shown in Fig. 2, is disposed inside of the enclosure 30 and is mounted upon the upper edge of the wall 22 of the well. It is disposed for flexure in the upwardly open recess or well. vIt is held against such upper edge land overlies the edge by an annular solenoid supporting plate 44 which hears against the diaphragm and is held thereagainst by a plurality of securing bolts or the like 46. It will be noted that the solenoid supporting plate serves a dual function of both supporting the solenoid and of securing the diaphragm to the base 10. When the bolts 46 are tightened down against the plate 44, .they urge the same against the diaphragm and squeeze the diaphragm between the plate and the base 10. A sealing Vconnection is thereby formed with the diaphragm against `the base 10. It will also be noted that the O-ring gasket 36, the solenoid supporting plate 44, and the diaphragm 40 cooperate to seal the open end of the enclosure 30, and prevent the escape of oil within the enclosure outwardly of the solenoid.

The solenoid 32 shown in the drawings isfof conventional construction. It may comprise a generally U-shaped frame, or what may be termed a C-stack 48 housing a solenoid coil 50. A solenoid plunger 52 generally T-shaped in cross section is adapted to reciprocate within the frame through the coil 50 under the inuencefof a magnetic iield created bythe coil. Thetop of the U-shaped frame may be bridged by a shock-absorbing element or the like 54 and against whichthe head portion 56 of the plunger bears when itreturns upwardly. from its retracted position. kItis to be understood that when the coil 50 is energized the plunger is attracted downwardly, and when the coil is de-energized, the plungeris permitted to return to its uppermost position under the influence of a springtor the like in the device 16 to be actuated. The lower surface of thelhead portion 56 of the plunger is adapted to abut the upper ends of the U-shaped frame 48 along the line indicated in the drawings at 58. The head 56 is provided with shading coils which hold the head ofthe plunger -against the upper ends of the arms of the frame. It will be noted in Fig. 2 that the plunger is in itsretracted position downwardly in the frame and that the meeting surfaces of the underside of the head 56-aind the upper edge of the U-shaped frame are in abutment along the line V56, and that the lower end 60 of the plunger is spaced a slight distance above the upper surface of kthe bottom of the U-shaped frame. It is apparent-thatif the meeting surfaces of the plunger and the U-shaped frame along the line 58 were to wear away sutliciently, the vlower end 60 'of the plunger would abut the upper surface of the bottom of the U-shaped frame. 'Suchabutment would even- 'tually tend to prevent the head 56 from properly seating .upon the upper ends of the arms of the U-.shaped frame, and when this `occurs the shading coils fail to hold the plunger seated and the plunger will chatter. A chattering plunger is incapable of holding the same load as one which does not chatter. It tends to heat up and burn out the coil of the solenoid.

Received within the lower Aend of 'the U-shaped frame 48 and within the annular solenoid-supporting plate 44 is a bearing insert 62. The insert is provided'with a `shoul- Vder 64 adapted to bear against the yupper surface of the plate 44 and be disposed within a complementally shaped `recess in the U-shaped frame 48. "The-solenoid frame is held down upon the supportingplate44` in--any convenvient manner and grips the inse1t`62 .between-the-ffrarne and the plate.

The insert is providedv witha-central Aaperture 65 through which extends thefshort pinfor rod=66randiwhich supported inuthe insert invbearing'relation therewith.

6 The insert is adapted to guide the movements of Athe -pn 66 when the plunger 52 of the solenoid abuts the pin and urges it downwardly, or when the stem 18 of the device is urged upwardly under the influence of a spring or the like in the device. The aperture Yin the insert A62 is in alignment with the aperture 26 in the base.

As sho-wn in Fig. 2 the diaphragm is provided een, trally thereof with an abutment member or a button 68. One form of the button is shown in detail in Fig. `3 and includes an upper annular plate 68-a and a lower annular plate 68-b provided with an upwardly extending boss 68-c adapted to be received through an aperture in the diaphragm and through an aperture in the upper plate 68a. The two plates are held together and upon the diaphragm by the peened-over portion 69 of the boss 68-c. The upper plate 68-a and the lower plate 68,-1; are provided with annular complementally shaped ridge and groove equipments indicated in the drawing `at 71 and 73 respectively. The diaphragm is adapted to be gripped between the ridge and groove equipments to ensure the retention of the button centrally of the diaphragm and in alignment with the aperture therethrough, through which extends the boss 68-c. The boss 68-c and the lower plate .68-b are adapted to withstand and transmit the forces between the pin 66 and the lower pin hereinafter to 'oe described. With the provision of the boss 68-c the upper plate 68-a is not compressed toward the lower plate 68b and therefore the diaphragm is not squeezed between the plates during the action of the solenoid.

Disposed beneath the diaphragm is another pin 70 which is slidingly received within the aperture 26 in the oase 1t), and which is adapted to abut at its upper .end the button 68 and at its lower end the stem 18 of the device 16 to be actuated. This pin is adapted to transmit the force of the plunger upon pin 66 and against button 68 to the stern 18 to urge the stem downwardly under the influence of the downward movement of the plunger. Pin 70 is also adapted to transmit the upward force of the spring in the device 16 against the stem 18 to the button 68, pin 66, and thence to the plunger 52, to urge the latter upwardly in the solenoid frame Vwhen the coil is de-energized.

Because of the provision of the pleat 42 in the diaphragm, the diaphragm may be exed downwardly into the well 20 without tending to stretch the diaphragm. The fold of the pleat 48 is sufficient to accommodate the downward movement of the diaphragm.

The enclosure 3i) is provided with an oil-iilling aperture closed by a plug 72. The enclosure is also provided with an electric lead plug as at 74 which is provided with a pair of electric leads 76 and 78 which in -any convenient manner are sealed within the plug 74 and extend therethrough into the inside of the enclosure as shown `at 76' and 7S. Electric leads (not shown) connected at 76 and 78 extend to the coil 50 `to electrically connect the Same with the outside leads 76 and 78. yThe enclosure may be filled with oil as, for example, to .the level indicated at St). The oil found desirable for use in the enclosure has been conventional hydraulic brake fluid oil. Ordinary mineral oil has also been found to be very suitable. rEhe prime requisites of the oil-are that it must be capable of conveying heat from the solenoid to the walls of the enclosure and also be capable of acting as a lubricant for the meeting faces of the plunger and U-shaped frame 48, and for the other moving parts of the solenoid.

In the operation of the unit shown in Figs. l and l2, and assuming that the plunger 52 is in its retracted position upwardly against the upper inside surface 'offthe butter member S4, upon energization of the coil 50,\the plunger will be attracted into the coil and downwardly toward the diaphragm. As the plunger -moves downwardly through the oil filling the Yenclosureandv nears its downwardmost position, for example, when it is spaced substantially .001 from the upper surface 82 of the frame 48, a thin lm of the oil will exist between the meeting faces of the plunger head 56 and the surface 82. This thin iilm of oil tends to resist continued downward movement of the plunger. However, under the constant influence `of the magnetic ield created by the coil 50, this thin lm of oil is almost squeezed out from between the meeting surfaces 82 of the frame. During this last increment of travel of the plunger in squeezing the oil lm out from between the meeting surfaces, the plungers downward movement is slowed almost to a complete stop. Its movement through this last .001" of travel is very slow, such that when the plunger is nally seated against the upper face 82 of the frame, it is brought up against such face gently. Such gentle contact of the head 56 of the plunger with the upper surface 82 of the frame prevents the wearing away of these meeting surfaces and therefore prevents the plunger from chattering after long continued use.

The operation of the plunger from its extended to its retracted position may be very rapid because the cushioning effect of the oil film does not occur, for example, until the last .001" of travel of the plunger. This rapid movement, as is well known by those skilled in the art, is important to the proper functioning and life of the solenoid, and therefore it is important that such movement be slowed only at the very end of the movement of -the plunger.

In Fig. is shown a modification of the abutment member. Such abutment member includes a stem portion 90 4and a pair of centrally apertured disc-like elements or plates 92 and 94. The upper end of stem 90 has a reduced diameter portion 96 which extends through the elements 92 and 94, and forms a shoulder 97. The upper end of the reduced diameter portion 96 may be peened over as at 98 to secure the elements 92 and' 94 in gripping engagement upon opposite sides of the diaphragm upon the end of the stem 90, with element 92 abutting the shoulder 97. Rib and groove equipments 101 and 103, similar to those described in connection with Fig. 3, are provided in the plates to prevent the diaphragm and abutment member from shifting relative to one another.

The lower end of the stem 90 is received within the aperture guideway 26 in the base 10. Its lower end is adapted to abut the upper end of hte actuating rod 18 of the device to be actuated. Above the diaphragm, and adapted to abut the peened end 98 of the stem, is a spacer pin 102 which abuts at its upper end the plunger 52. The advantage of the construction shown in Fig. 5 over that shown in Fig. 3 is that the abutment member 92, and consequently the diaphragm, are guided during their reciprocal movements by virtue of the sliding fit of the stern 90 within the guide aperture 26. With the construction shown in Fig. 3, there is nothing which ensures movement of theabutment member and consequently the diaphragm along an axis perpendicular to the normal plane of the diaphragm. With the provision of the sliding tit of stem 90 in the aperture 26, the diaphragm is prevented from twisting at its center and therefore its life is prolonged because it is not subjected to undue stretching as it is flexed.

In Fig. 6 is shown still another modification of the but-ton or abutment member shown in Fig. 3. In Fig. 6 the button or abutment member includes a stem 104 which is slidably received within the insert 62, with the lower end of such stem being received through a pair of centrally apertured discs, elements or plates 110 and 112 with the end of the stem being peened over to grip the plates between such end and the shoulder of the stem.

It is apparent that the construction shown in Fig. 6 is very much similar to thatrshown in Fig. 5 with the parts reversed. A spacer element or actuating part 106 is slidably received within the base 10 and is adapted to abut at its lower end the actuating rod 18 and at its upper end the peened portion 108 of the stem 104. The plates 110 and 112 which are disposed on opposite sides of the diaphragm 40, grip the diaphragm with the ribV and groove equipment, and are securely anchored to the diaphragm between the peened-over end 108 and the shoulder 109 of the stern.

The actuating part 106, it should be understood, may

be eliminated if the stem of the device to be actuated extends sufliciently far into the base 10. It will also be noted that the insert 62 in Fig. 6 guides the movement of the stem 104 and consequently the movements of the diaphragm, and prevents twisting of the diaphragm. The oil filling the enclosure is a much better conductor of heat than is air. The oil lling the enclosure is in intimate contact, as hereinabove mentioned, with all of the parts of the solenoid. Because of this any heat given off by the solenoid is conducted through the oil to the walls ofthe enclosure. The surface of the enclosure exposed to the atmosphere is of a much greater area than would be the surface of the solenoid if it was mounted in the atmosphere as are present-day solenoids. Because there is a greater amount of surface exposed to the atmosphere in the instant construction there is a larger surface to transfer heat to the atmosphere. Therefore, our solenoid unit serves to conduct heat generated by the solenoid more rapidly into the atmosphere than is at present possible with the conventional solenoid. This materially increases the life of the solenoid because the solenoid will not heat up as much though it be used constantly and repeatedly over a long period of time.

Shown in Fig. 7 is a modified form of our invention which includes, as does the Figs. 1 and 2 embodiment, a closed housing in which a solenoid is disposed, with an oily fluid illing the housing and enveloping the solenoid. The unit comprises a base 120 having a solenoidsupporting surface 122 which is centrally recessed as at 124. A solenoid 126, having a supporting plate 128, is

' mounted, by means of screws 130, upon the base 120. The

solenoid includes a plunger 132 which is adapted to re,- ciprocate through the coil 134. The plunger has a shank portion 136 which extends through the coil, with the lower end of the shank adapted to abut the upper end of the spacer pin 138. The lower end of the spacer pin is adapted to abut the head 140 of the actuating rod 142 which extends through the base 120. The spacer pin slides within a bushing 144 mounted in the solenoidsupporting plate 128.

The base is secured, as by means of bolts 146 or the like, to the device to be actuated 148. Variously shaped bases may be employed to suit the particular application in which a solenoid unit is to be used. The head of the actuating rod 142 is disposed within the recess 124 in the base and moves therein from an extreme lower position to an extreme upper position.

Below the head the rod is encircled by an improved sealing means, received within a counterbore in the base, and through which sealing means the rod reciprocates and is guided for reciprocation. Such sealing means comprises a bushing 150, shaped as shown in Fig. 7, and provided with a pair of axially spaced apart external grooves within one of which is received an O-ring gasket 152 adapted to bear against the wall of the counterbore within which the bushing is received. The other grooveindicated at 154 communicates with a drain hole 156 extending through the base. An internal groove 158, concentric with groove 154, is formed in the bore 160 of the bushing, and communicates with groove 154 by'means of a small cross aperture 162. A pair of O-ring gaskets 164 and 166 encircle the rod at opposite ends of the bushing seated within suitably provided recesses. The lower of these recesses muy have a lip 168 9` to hold the O-rng 166 in place. The 0-ring gasket 164 is adapted to form a fluid-tight seal about the actuating rod 142 and prevent the escape of oil from the solenoid chamber downwardly along the rod. The O-ring gasket 166 is adapted to form a fluid-tight seal and prevent any 'uid'that may be in the device 148 from creeping up along the actuating rod. In the event that huid does creep by the O-ring gaskets, it will be collected in the internal groove 1-58 and from there will drain outwardly through the` cross aperture 150 into the drain hole 156 and fromy there outwardly of the solenoid unit. Upon inspection of the solenoid unit it may be readily determined whether or not either of the O-ring gaskets 164 and 166 is defective, because if either is so, it will be noted that oil is escaping from the drain hole 156.

The lower end of rod' 142 is adapted to abut or be coupled with that part of device 148 which is to be actuated. The device 148 may be provided with a spring or some other means not shown, which normally urges the part to be` actuated toward the connecting rod 142. This` spring or other means serves to maintain the rod and the plunger in a` normally extended position, i.e., the plunger is moved to the dotted outline position in Fig. 7v with the head 168 in abutment with the cover 170. Upon energization of coil 134 the plunger is retracted or sucked into the coil to the solid` outline position; This movement of the plunger into the coil is against the action of the spring or other means inthe device to be actuated. When the electric current to the coil is interrupted, the plunger is immediately returned tothe dotted outline position with the head 168 abutting thev cover 17.0.

The cover 170 is received over the base 120 and sealed thereon in fluid-tight relation by the O-ring gasket 172 seated in a suitable groove in the base. Screws or the like 174 extend through the cover to secure it to the base. It'willbe noted that screws 174 extend through the cover and into the base below the O-ring gasket 172, and therefore the need. for sealingr the entry of the screws through the coveris eliminated. A ller opening 176 extends through the cover and is adapted to be closed by a suitableplug. Thecover shown in Fig. 7 is adapted for use withv a solenoid intended to be operated` on its side, that is to say, the axis of movement of the plunger lies in a. horizontal plane with the tiller opening 176 on top. The drain hole 156 would then be disposed to open downwardly. The housing is tilled with oil, as above described in conection with Figs. 1 and 2.

An electric lead wire 178 running from the coil 134 outwardly of the solenoid unit through the base and into the device to be actuated, is shown in Fig. 7. There are generally two such wires, but only one is shown for convenience, it being understood that the other wire is similarly disposed and arranged. Instead of extending into the device to be actuated, the lead wire may extend through the side of the base above the device. The wire is received through an aperture 180 in the solenoid-supporting plate as shown in Fig. 8, and through a hole 182,

extending through the base 120. Just beneath plate 128 isa cone-shaped countersink 184, within which is disposed an O-ring gasket 186. Upon securing the solenoidsupporting plate 128 to the base, the gasket 186 is compressed in the countersink and is squeezed about the Wire 178 to form a huid-tight seal thereabout and between the wire and the base.

The -spacer pin 138, mentioned above, is formedv preferably of a somewhat resilient material such as nylon. We have discovered that. a pin formed of this material rather than metal, will cushion the shock on the plunger when it moves downwardly to actuate the device 148. When a steel or brass pin is used, the plunger may not lastV for more than a few million cycles of operation, but with a nylon pin, the plunger may operate through many morey times this number ofk cyclesv without showingevivItl dence of breaking up. In Fig. 9a modified form of the pin 138 is shown. In this gure the pin has a body- 190 formed of metal such as brass or steel, with a pair of nylon caps 192 and 194 at each end. In cross section these caps are generallyl T-shaped with the `shank of the T press fitted within suitable recesses formed in opposite ends of the pin. This form of the pin is particularly suitable where the pin must be of a longer length or where it is desirable to have a metal-to-metal Contact between the pin and the bushing 144.

In the operation of the solenoid unit shown in Fig. 7, the plunger, upon energization of the coil, is sucked into the coil with the spacer pin 138 and the oil in the housing dampening the shock. The manner in which the oil dampens the shock is explained hereinabove with respect -to the construction shown in Figs. 1 and 2. Upon the return stroke of the plunger shown in Fig. 7, that is to say, upon .the return from the solid outline position to the dotted outline position, the head of the plunger abuts the cover 170. The oil which lls the housing is squeezed out from between the head of the plunger and the cover, and slows the movement of the plunger to almost a complete stop at the very last increment of the plungers movement, in a manner similar to the description of the dampening effect of the oil in connection with the Figs. l and 2 structure. It will be noted that in Fig. 2 the solenoid is shown as provided with a butter element 54. In the Fig. 7 construction, the buffer has been eliminated and the oil serves as the buffer. Therefore, in the Fig. 7 construction the oil is relied upon to dampen the movements of the plunger at the opposite ends of its stroke.

In Fig. l0 we have shown an improved fluid-sealing if a solenoid is mounted on the base, that it is necessary' to thread the lead wire down through the Wire-receiving hole 182 to connect it somewhere to a source of electric current. The connector shown in Fig. l0 will eliminate the necessity of threading the lead Wire into or out ofv the base in removing or replacing the solenoid, and yet will ensure a fluid-tight seal. As will be apparent, the connectors shown, while particularly adapted for use in an oil bath solenoid, will be equally useful and effective with conventional solenoids.

The connector includes a pair of bell-shaped gaskets 196 and 198 which may be formed of neoprene or other synthetic rubber-like material capable of withstanding the destructive effects of oil. Spacing the gaskets apart is a hollow body portion 200 of insulating material such as* Bakelite, the ends of which are countersunk to conform to the tapering meeting surfaces of the gaskets 196 and 198. A pair of contacts 202 and 204 are disposed within the body and held tensioned apart by the resilient spring element 206 formed of an electrically conductive material. The lead wire 178 is cut short and contact 202 is secured to the end of it. To the cut end of the remainder of the lead wire 178, which remainder is indicated at 178-a, is secured the other contact 204. The gasket 196 is disposed beneath the solenoid-supporting plate with the neck 208 received within the aperture 180 of the plate. The basey is counterbored as at 210 to receive the connector therein, with the bottom 212 of the bore serving as a shoulder upon which the gasket 198 rests, such that the connector is gripped between the bottom 212 of the bore and the solenoid-supporting plate when the plate is secured to thebase. When the solenoid-supporting plate is tightened down upon the base, the gaskets 196 and 198 are squeezed: against the connector body 200and against the lead wires 178 and 178-a which extend through the gaskets,

`and an effective uid-tight seal is formed about the wires.

It is apparent that upon removal of the solenoid and plate from the base, the gasket 196 and the contact 202 will be lifted out of the counterbore 210 and out of contact with the remainder of the connector, and an electric circuit through the connector will be broken. Therefore the source of electric current to the solenoid need not be interrupted while the solenoid is being removed, nor while it is being mounted on the base, as the workman need not touch a possible hot wire. It is also apparent that this connector both forms a fluid-tight seal and also effectively electrically connects the lead wire 173 to the source of electric current, merely by inserting the contact 202 into the connector and tightening the solenoid and plate down upon the base.

Shown in Figs. 11-14 is another modication of our oil bath solenoid unit. This modification represents an improvement upon the modications shown in Figs. 1-10,

inclusive, and is adapted to automatically effect, when placed upon and secured to the device to be actuated, the mechanical actuating connection and electrical connection. The device to be actuated is provided with a part which a moving actuating rod means in the unit engages, and is also provided with electric lead wires extending up to that surface of the device upon which and over which the solenoid unit lies. The result of providing a unit of the character shown in Figs. 11-14 is that the attendance of two workmen to install or remove the unit is unnecessary. Under existing union regulations, when la solenoid is to be placed upon or removed from a hydraulic vaive or the like, both an electrician and a hydraulics mechanic must be present, the former effecting or disconnecting the electrical connection, and the latter removing the screws or bolts which hold the solenoid to the device to be actuated. With the unit shown in Figs. l1-14, there are no electrical wires to be connected or disconnected which will require the attendance of an electrician, and therefore the unit may be installed or removed by only the hydraulics mechanic. This will effect a substantial saving in labor.

As shown in Fig. 11, the unit includes a closed housing within which is disposed a solenoid having a reciprocable plunger, with means positioning the solenoid within the housing, and with the housing filled with an oily fluid which envelops the solenoid. Actuating rod means extends outwardly of the housing and is adapted to engage at one end of the plunger of the solneoid and at the other end the movable part of the device to be actuated upon which the solenoid unit is mounted. Sealing means encircles the actuating rod means to prevent the escape of the oily uid out of the housing along the actuating rod means. A pressure relief valve and an inspection drain are provided with the former serving to prevent bursting of the housing if the heat of the solenoid increases the pressure within the housing, and with the latter serving to indicate visibly any leakage of oily fluid out of the housing along the actuating rod means.

rl`he housing is generally indicated at 220, and includes a base portion 222. Within and forming a part of the base portion 222 is a removable end wall 224, upon which and against which the solenoid, generally indicated at 226, is seated. The housing includes a cover 228 which is received over and cooperates with the end wall portion 224 to form a closed receptacle, enclosure, or housing.

As shown in Fig. 12 the cover 228 may be generally cylindrically shaped and is adapted to closely surround solenoid 226. The base portion 222 of the housing may be provided with outwardly extending anges 230 through which bolts or the like 232 may be extended for the purpose of securing the unit to the device to be actuated. The solenoid 226 is supported, as shown in Fig. 13, upon a rubber cushion or the like 234, which overlies the end wall 224. The end wall may be provided with a pair of upstanding ears 236 between which the solenoid frame or G-stack 238 is received. The ears 236 serve to position the solenoid rotation-wise within the housing. A coil spring 240 bears at its lower end `against the upper edge of the C-stack and at its upper end against the underside of the cover 228, and tensions the solenoid down against the rubber cushion 234. Ears 236 and the rubber cushion 234 and the coil spring 240 provide means to resiliently support the solenoid within the housing. No bolts, screws, or the like are required to position the solenoid in the housing with the provision of ears 236, cushion 234, and the spring 240, and for this reason it is apparent that the mounting of the solenoid within the housing is of a simple character and that the solenoid may be readily assembled and disassembled within the housing.

The upper end of cover 228 may be provided with a boss or the like 242 through which is threadedly received a combination packing and bushing nut 244. A reset button 246, as shown in Fig. 13, is received through the nut 244 and upon being urged downwardly will move the plunger 248 of the solenoid downwardly, when the latter is in its uppermost position. The pin 246 may be provided with an annular groove within which is received an O-ring gasket 256 to seal the pin 246 within the nut. Suitable gasket means, such as a copper packing ring 252, may be received beneath the flange of nut 244 and the upper surface of boss 242.

The solenoid 226 is of conventional construction in that it includes, as mentioned above, a C-stack 238 consisting of a plurality of laminated generally U-shaped plates held together by rivets or the like, not shown, with a pair of plunger buffer frames 254 and 256 overlying opposite sides of the C-stack. Bolts or the like 258 extend through the C-stack and the Vframes to secure the trames to the stack. The upper ends of the frames are shaped as shown in Figs. 11 and 13 to provide butter carrying ears 260 and 262. A butter plate 264 extends through apertures in ears 26() and 262 with a neoprene 0r the like cushion 266 received within the U-shaped ends of the plate 264 to bear against the upper edge of the apertures or slots in ears 260 and 262, to thereby cushion plate 264 within the ears. For a more detailed description of the construction of this solenoid, reference should be made to the patent of H. W. Jencks #2,671,187. The plate 264 is provided with an aperture through which pin 246 may be extended to abut plunger 248.

The end Wall 224 of the base portion of the housing is provided with an aperture extending therethrough and coaxially aligned with the reciprocatory movement of plunger 248. Received within such aperture is a bushing 268, with an O-ring gasket 27@ disposed at the lower end of a counterbore of the aperture. The bushing 268 overlies the O-ring gasket to retain the same in the aperture. The O-ring gasket encircles actuating rod means 272 which is received for reciprocatory movement within the bushing 265. The O-ring gasket serves to prevent the passage of oily lluid in the housing outwardly therefrom along the actuating rod means 272.

Actuating rod means 272 includes a two-piece rod having a tool steel lower end portio-n 274 and a softer metal upper end portion 276. The upper end portion may be formed of brass or beryllium copper. The beryllium copper or brass is a magnetic insulator and prevents the lines or" ilux from passing from the plunger directly down to the laminated plates at the bight of the C-stack. If this upper portion of the actuating rod means is of a magnetically conductive material, the sucking power of the solenoid would be materially reduced because the lines of flux could pass directly through the actuating rod means to the plates at the bight of the stack. The upper portion 276 may be provided with a reduced diameter portion 278 which is received within a complementary recess formed in the upper end of the tool steel portion 274. Portions 274 and 276 may be welded together as at 280.

The base portion 222 of the housing may be internally provided with an encircling snap ring receiving groove 282 within which a 'snap 'ring284 is received to hold the erid wall 224 in place withinth'e housing'a'nd 'against the action of coil vspring 240. Cooperating shoulders indicat'ed at 286 on the cover 228 and the end Vwall 224 position the end 'wall within the housing. An O-ring 288 received within a provided groove in end Wall 224 cooperates with the cover 228 Vto seal the end 'wall in the housing.

The solenoid unit is shown as being mounted upon an adapter plate 290. The adapter plate is mounted upon the device to be actuated by the solenoid unit and adapts the device for mounting of the unit thereupon. In certain instances the adapter plate may be eliminated where the device to be actuated is especially designed for actuation *by an oil bath solenoid'unit of the character shown in Figs. 11-13. Once the adapter plate is mounted upon the device to be actuated, it may vbe considered an integral part ofthe device and is left atlixed thereto when the solenoid unit is removed from the device for either servicing or replacement. The adapter plate includes an aperture 292 extending therethrough and into which the actuating rod means 272 extends. A visible inspection drain groove or the like 294 may be formed in the adapter plate to open at one end into the aperture and open at the opposite end outwardly of the plate such that any leakage of oily fluid out of housing 222 by the O-ring gasket 270 will be visibly evident. In addition, any leakage of, for example, hydraulic fluid out of a valve or the like upon which the unit may be mounted, will also be evident upon inspection of groove or passageway 294.

A pressure relief valve comprising a spring-loaded ball member 296 may be received in a suitably provided recess'in the end wall 224, with the ball serving to relieve excessive pressures developed within the housing through excessive heating of the oily tluid therein by a solenoid. The pressure relief valve communicates, as shown in Fig. 13, with the passageway 294.

In order to automatically effect an electrical connection between the solenoid unit and the device upon which the unit is mounted, when the unit is mounted upon such device, and'effedtan electrical disconnection of the unit when the same is removed from the device, cooperating electric terminal means are provided. `Such cooperating electric terminal means comprises a male terminal 298 which is mounted within the end wall 224 of the base portion of the closed housing. A female terminal 300 is mounted within the adapter plate 290. The male terminal includes an insulated body portion 302 of rubber, neoprenepor theilike, xedly received within a provided apertureinf-the end wall 224. A pair of metal connectors 304 are xedly received within the body portion 302, with screws306 threaded into the connectors. Leads 308 connect the 'solenoid coil 310 to the connectors 304.

The female Vterminal portion 300 includes an insulating body 310 within which are received a pair of metallic connectors 312, 'asshown in Fig. `14. Electric leads 316 are connected with-'the connectors 312 and serve to electrically connectconnectors 312 to a source of electric power. The leads 316 may extend into and through the device to be actuated. While only one electric lead 316 is shown, it `will'he understood that two are provided.

The adapterplatemay be provided with a plurality of apertures 318 through which bolts or the like may be extended to'secur'e 'the plate to the device to be actuated. Threaded apertures-320 are adapted to receive the bolts 322 for securing the unit to the adapter plate. Upon placing the solenoid'unit upon the adapter plate with the male and female electric terminals interengaged, the actuating rodme'ansf272'extends into aperture 292. in position to engage the part to be moved in the device to be actuated by the solenoid unit. The bolts 232 are tightened in apertures 320 toeffect the securement of the unit to the device. Thus it ywill be seen that upon connecting the unit to the adapter plate mounted on the device to be A14 actuated, 'the electrical connection, and the mechanical connection with the part to be moved are simultaneously and automatically etected.

The inner walls of the cover 228 may be provided with increased thickness portions 322 having flat faces 324 adapted to both strengthen the cover and bear against the ears 236 to position end wall 224 rotation-wise within the cover 228.

What we claim is:

l. An oil bath solenoid adapted to be mounted as a unit upon a device to be actuated having a part to be shifted and fixed electric terminal means both located beneath the unit when the unit is mounted upon the device comprising, in combination: a closed housing inciuding sealingly connected base and cover portions, means cooperating with one of said portions to secure the housing to the device to be vactuated with the hase portion juxtaposing said device, a solenoid disposed within the housing having a reciprocable plunger, means within the housing bearing against the solenoid and the housing to seat the solenoid upon said base portion, said base portion provided with an aperture therethrough, actuating rod means extending through the aperture to abut the plunger and be shifted thereby, fixed electric terminal means on said base portion with electric leads connecting such terminal means to the solenoid, an oily fluid filling the housing and enveloping the solenoid and bathing the plunger, gasket means encircling said actuating rod means and cooperating with the aperture to seal the rod means in the aperture, said actuating rod means and the electric terminal means on the base portion both adapted to engage, respectively, the said part to be shifted and the said lixed electric terminal means on the device to -be actuated when the base portion juxtaposes the device.

2. An oil bath solenoid unit comprising, in combination: a closed housing having a base portion; a solenoid in the housing having a reciprocable plunger; said base portion provided with an aperture therethrough; actuating rod means extending through said aperture to be engaged and shifted by the plunger; means in said aperture cooperating with the rod means to seal the rod means in the aperture; an oily uid in the housing enveloping the solenoid and bathing the plunger; electric terminal means on the base portion connected to the solenoid; and means to support the housing on a device to be actuated and having electric terminal means cooperable with the terminal means on said base portion to automatically effect an electric connection when the housing is placed on said supporting means and connected thereto, such latter means provided with an aperture through which said actuating rod means or a part to be actuated may extend; and means for connecting the housing to the supporting means.

3. The invention as dened in claim numbered 2 chareterized in that the supporting means is provided with an aperture therethrough alignahle with the aperture in said base portion, and said supporting means is provided with an inspection drain passageway opening at one end into the aperture Ithrough the supporting means and opening at the opposite end outwardly of the supporting means.

4. The invention as defined in claim numbered 2 characterized in that a relief valve is disposed in the housing with the discharge side thereof opening outwardly of the housing with the valve operable to relieve excessive nressure developing in the housing.

5. The invention as defined in claim numbered 2 characterized in that a relief valve is disposed on said base portion of'the housing with the discharge side of the valve communicating with a drain passageway in said supporting means opening outwardly of the supporting means.

6. in an oil bath solenoid assembly for shifting a part to be actuated, an hermetically closed housing, a solenoid in the housing having a reciprocable plunf'er, actuating rod means vsealingly extending through a wall of the housing and reciprocably supported therein in substantially coaxial alignment'with the plunger and {loatingly connected to the plunger to be shifted by the plunger upon energization of the solenoid, and an oily fiuid filling the housing and enveloping the solenoid and bathing its plunger and the floating connection between the plunger and actuating rod means.

7. The invention as defined in claim 6 characterized in that a diaphragm cooperates with said actuating rod means and with the housing to prevent leakage ofthe oily fluid out of the housing around said actuating rod means.

8. An oil bath solenoid for removable securement to a device to be actuated .having a part to be shifted, comprising, in combination: an hermetically sealed housing having an end portion for juxtaposition on the device to be actuated, a solenoid in the housing having a reciprocable plunger shiftable with respect to said end portion upon energization of the solenoid, actuating means extending sealingly through said end portion and supported therein for reciprocation substantially coaxially with respect to the plunger and oatingly connected at one end to said plunger to be shifted thereby upon energization of the solenoid and engaging at the other end the said part of the device to be actuated, an oily fluid filling the housing and bathing the solenoid and plunger and the floating connection between the plunger and said actuating means, and securing means adjacent said end portion for securing the housing to the device to be actuated. f

9. An oil bath solenoid assembly as defined in claim 8 characterized in that said means floatingly connected at one end to the plunger is iioatingly connected at the opposite end With the part to be actuated to shift the same.

10. An oil bath solenoid unit for removable securement to a device to be actuated having a part to be shifted, comprising, in combination: an hermetically sealed housing having opposite end wall portions with one end Wall portion adapted for juxtaposition on the device to be actuated, a solenoid in the housing having a generally U-shaped flux conducting frame extending substantially normal to said one end wall portion, a solenoid coil in said frame seated at one end against the base of the U- shaped frame, the arms of said frame having portions extending over the opposite end of the coil and providing flat surfaces extending substantially normal to the axis of the coil, a reciprocable T-shaped plunger oatingly received in the coil and frame and shiftable substantially normal to said one end wall portion of the housing upon energization of the solenoid, the underside of the head of the T-shaped plunger having generally fiat surfaces extending substantially normal to the reciprocating travel of the plunger and confronting said at surfaces of the frame and abutting such surfaces at the end of the plungers stroke upon energization of the solenoid to limit the travel of the plunger, said plunger having a length such in relation to the frame that when said surfaces are in abutting relation that end of the plunger opposite the head is spaced from the base of the frame, actuating means extending sealingly through one of said end wall portions of the housing and supported for reciprocation substantially coaxial with the plunger and floatingly connected at one end to said plunger to be shifted thereby upon energization of the solenoid and engaging at the other end the said part of thev device to be actuated, an oily fluid filling the housing and bathing the solenoid and its plunger and said iioating connection between the plunger and said actuating means and providing an oil film between said confronting surfaces, and means for removably securing the housing to the device to be actuated.

ll. rThe invention as defined in claim l characterized in that said actuating means is a rigid pin-like member abutting that end of the plunger opposite the head end to be pushed outwardly of the housing upon energization of the solenoid coil.

l2. The invention as defined in claim 10 characterized in that one of said end Wall portions is removably seal- 16 ingly secured to the housing for removal or replacement of the solenoid in the housing and said actuating means comprises a rigid pin-like member extending sealingly through such removable end wall portion, and such end wall portion of the housing is adapted to juxtapose the device to be operated.

13. In an oil bath solenoid assembly for shifting a part to be actuated: an hermetically closed housing, a solenoid in the housing having a reciprocable plunger, actuating rod means extending sealingly through a wall of the housing and pushable outwardly of the housing by the plunger upon energization of the solenoid, an oily fiuid filling the housing and bathing the solenoid and plunger, said actuating rod means pushable outwardly of the housing by Huid pressure in the housing acting against it, and a fluid pressure control valve communieating with the interior of the housing and vented to the atmosphere for allowing escape of excessive fiuid pressure in the housing acting against said actuating rod means.

14. An oil bath solenoid assembly comprising, in combination: an hermetically sealed housing having a removable end Wall, a solenoid in the housing having a flux conducting frame and a reciprocable plunger shiftable with respect to said frame upon energization of the solenoid, said end Wall cooperating with the solenoid to position the solenoid in the housing, means extending sealingly through an end of the housing and supported in such end for reciprocation to be shifted by the plunger upon energization of the solenoid and floatingly connected to the plunger, and oily fluid filling the housing and bathing the solenoid and its plunger and said floating connection.

15. The invention as defined in claim 14 characterized in that said reciprocable means extends sealingly through the removable end wall of the housing.

16. An oil bath solenoid unit for removable securement to a device to be actuated having a part to be shifted and electric terminal means disposed adjacent said part, comprising, in combination: an hermetically sealed housing having an end portion for juxtaposition on the device to be actuated, a solenoid in the housing having a reciprocable plunger shiftable with respect to said end portion upon energization of the solenoid, actuating means extending sealingly through said end portion and supported thereby for reciprocation substantially coaxially with respect to the plunger and fioatingly connected at one end to said plunger to be shifted thereby upon energization of the solenoid and engaging at the other end the said part of the device to be actuated, electric terminal means on said end portion of the housing electrically connected to the solenoid and disposed to be urged into engagement with said terminal means on the device to be actuated when said end portion of the housing juxtaposes such device and said actuating means engages said part to be shifted.

17. An oil bath solenoid unit for removable securement to a device to be actuated having a part to be shifted comprising, in combination: an hermetically sealed housing having at one end a removable wall, a solenoid in the housing'having a ux conducting frame and a reciprocable plunger shiftable with respect to said frame and substantially normal to said removable wall upon energization of the solenoid, said frame and plunger having generally'at confronting surfaces extending substantially normal to the reciprocating travel of the plunger and substantially abutting each other at the end of the `plungers stroke upon energization of the solenoid to limit the travel of the plunger, actuating rod means extending sealingly through said removable wall and supported therein for reciprocation substantially coaxial with the plunger and oatingly connected at one end to said plungerV to be pushed outwardly thereby upon energization of the, solenoid and engaging at the other end the said part of the device to be actuated, said actuating rod ofthe housing and vented to the atmosphere :for allowing escape of excessive uid pressure in the housing acting against said actuating rod means, and means for securing the housing to the device to be actuated with said removable wall substantially juxtaposing said device.

18. In an oil bath solenoid unit: a closed housing opening outwardly at one end and provided with an encircling Wall surrounding the opening and an outwardly facing shoulder spaced inwardly from the open end, a circular end closure member removably received within the open end of the housing and seated against said shoulder, said closure member having a peripheral groove opening outwardly toward said encircling wall, a gasket in said groove cooperating with the groove and the encircling wall to hermetically seal the closure member in the open end of the housing, a solenoid in the housing, spring means between the solenoid and one end of the housing holding the solenoid toward the opposite end of 18 the housing and tensioning said removable end closure member outwardly of the housing, and snap ring means cooperating with said encircling wall adjacent the open end of the housing and the closure member to hold the closure member in the open end of the housing counter the tension of said spring- References Cited in the le of this patent UNITED STATES PATENTS 1,166,699 Lutz Jan. 4, 1916 2,018,479 Zeininger Oct. 22, 1935 2,264,841 Gallagher Dec. 2, 1941 2,299,671 White Oct. 20, 1942 2,427,630 Snyder Sept. 16, 1947 2,544,491 Davis Mar. 6, 1951 2,547,390 Harris Apr. 3, 1951 2,564,221 Hornfeck Aug. 14, 1951 2,629,766 Vargo Feb. 24, 1953 2,647,181 Couts et al. July 28, 1953 2,694,165 Trombetta Nov. 9, 1954 2,698,159 Crum Dec. 28, 1954 2,714,141 U-rey et al. July 26, 1955 2,901,677 ohessman et a1 Aug. 25, 1959 FOREIGN PATENTS 769,907 Great Bri-tain Mar. 13, 1957 

